(Reuters) —Yellowstone
National Park managers have rejected a plan to use air rifles to
shoot the nation's last herd of purebred bison with so-called
biobullets containing a vaccine against a cattle disease, in a
decision that has riled the U.S. livestock industry.

Roughly half of Yellowstone's 4,600 bison are
estimated to have been exposed to brucellosis, a bacterial infection
that can sometimes cause cows and bison to miscarry.

Worries that infected bison may endanger cattle in states such as
Montana that border Yellowstone had prompted the powerful ranching
lobby to endorse biobullets — absorbable projectiles packed with
vaccine. They would cut disease rates among bison by as much as 35
percent over 30 years.

The proposal was the latest decades-long efforts to ease conflicts
between livestock interests and wildlife advocates over management
of Yellowstone bison.

Park officials said they decided against the remote vaccination
program because of its $9 million price tag, questions about its
effectiveness and the possible impact on the millions of visitors
who flock to the park to view iconic Western wildlife like bison.

The measure would have required shooting the animals once a year for
three decades, raising questions about how increased human
interaction could affect bison within the wild herd.

"We have concerns about how that repeated contact might impact bison
behavior and their visibility to park visitors," said Yellowstone
spokesman Al Nash.

Nash said there was no documented case of wild bison transmitting
brucellosis to cattle, which he said signifies the success of
existing measures designed to separate the park's herd from domestic
livestock.

Those practices include returning bison
that leave the park, testing and vaccinating bison that leave
Yellowstone, and slaughtering some infected animals.

Errol Rice, executive vice president of the Montana Stockgrowers
Association, said the threats posed by infected bison to Montana's
brucellosis-free certification, which protects the market value of
cattle, warranted using biobullets.

He said the program would have lessened the public outcry that
erupts when wandering bison are corralled and shipped to
slaughterhouses.

"The capture and removal of bison has been a challenging issue for
the park and Montana. Remote vaccination would have helped alleviate
the public relations burden we have to deal with when bison migrate
out of Yellowstone," he said.

Stephany Seay, spokeswoman for Buffalo Field Campaign, a bison
advocacy group, applauded the park's decision not to shoot bison
with vaccine.

"It was a mismanagement scheme based on a livestock model. We don't
vaccinate skunks against rabies or mosquitoes against West Nile
virus," she said.